Fracture toughness

<p>In <a href="/facts/Materials_science/N5HrXRYW">materials science</a>, fracture toughness is the critical <a href="/facts/Stress_intensity_factor/pLrUo683">stress intensity factor</a> of a sharp <a href="/facts/Fracture/nxDNAj0d">crack</a> where propagation of the crack suddenly becomes rapid and unlimited. It is a material property that quantifies its ability to resist crack propagation and failure under applied stress.   A component's thickness affects the constraint conditions at the tip of a crack with thin components having <a href="/facts/Plane_stress/2NXRCwo4">plane stress</a> conditions, leading to ductile behavior and thick components having <a href="/facts/Plane_strain/j4CJFdsU">plane strain</a> conditions, where the constraint increases, leading to brittle failure.. Plane strain conditions give the lowest fracture toughness value which is a <a href="/facts/Material_properties/Cg2LVoQe">material property</a>. The critical value of stress intensity factor in <a href="/facts/Fracture_mechanics/f9QogJzF">mode I</a> loading measured under plane strain conditions is known as the plane strain fracture toughness, denoted 
  
    
      
        
          K
          
            Ic
          
        
      
    
    {\displaystyle K_{\text{Ic}}}
  
. When a test fails to meet the thickness and other test requirements that are in place to ensure plane strain conditions, the fracture toughness value produced is given the designation 
  
    
      
        
          K
          
            c
          
        
      
    
    {\displaystyle K_{\text{c}}}
  
. 
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<p>Slow self-sustaining crack propagation known as <a href="/facts/Stress_corrosion_cracking/2ezVSAUP">stress corrosion cracking</a>, can occur in a corrosive environment above the threshold 
  
    
      
        
          K
          
            Iscc
          
        
      
    
    {\displaystyle K_{\text{Iscc}}}
  
 (Stress Corrosion Cracking Threshold Stress Intensity Factor) and below 
  
    
      
        
          K
          
            Ic
          
        
      
    
    {\displaystyle K_{\text{Ic}}}
  
. Small increments of crack extension can also occur during <a href="/facts/Fatigue_(material)/zmJY8hMt">fatigue</a> crack growth, which after repeated loading cycles, can gradually grow a crack until final failure occurs by exceeding the fracture toughness.
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Fracture toughness open-in-new

Fracture toughness